1. Field of the Invention
The invention relates to an MR apparatus for the reception of MR signals from an examination zone, exposed to a steady, uniform magnetic field and superposed gradient magnetic fields, after excitation by an RF magnetic field, using an MR coil system which includes a cylindrical coil system and a surface coil system.
2. Description of the Related Art
A magnetic resonance (MR) apparatus of this kind is known from EP-A 616 229. Therein, MR signals are received simultaneously from a plurality of regions of the body of a patient by means of a plurality of coil systems. The cylindrical coil system therein is, for example a bird-cage resonator conceived for examination of the head, while the surface coil system is, for example a quadrature coil system arranged on the chest of the patient. MR images of the head and chest regions can thus be formed during an examination. Generally speaking, a cylindrical coil system is to be understood to mean a coil system which has a cylindrical construction and encloses one or more parts of the body of the patient during an MR examination. The cylindrical coil system exhibits an essentially uniform sensitivity in the enclosed region and usually only one channel is required for the reception of the MR signals measured by the cylindrical coil system. A surface coil system, or surface coils incorporated therein, are to be understood to mean coils which are arranged on or in the vicinity of the surface of the body of a patient but do not enclose the body or parts of the body. Surface coils of this kind have a locally higher signal-to-noise ratio but also have a distinctly non-uniform sensitivity. One or two of such surface coils together usually require its own receiving channel.